The study of human immunology is often difficult because certain types of experiments can't be performed on humans for obvious ethical reasons. To facilitate human research, many scientists utilize animal models. The animal model of choice for immunologists is the mouse. This animal model is very useful because of the large number of reagents available as well as the creation of transgenic and knockout mice. Both types of mice are required for this program project grant. Transgenic carrying "humanized" MHC molecules will be iused to discover new epitopes for influenza proteins in project 2 and in project 3, they will be used to model human influenza infection in mice. Knockout mice are required so that the mouse endogenous MHC class I or II genes are not expressed in the MHC transgenic mice. Two projects will require some of the same strains of mice and procedures, so for continuity between the projects an animal core providing the necessary services is required. The specific aims of the animal core are: 1) to provide high quality housing, husbandry, and health care for the mice that are used in the studies proposed by Center investigators, 2) to provide a dedicated, stable space for the mice used in the proposed studies, and 3) to provide expertise in the delivery of viral vectors to mice to ensure proper biocontainment of the vectors and efficient immunization of experimental animals.